In general, a machining tool is used in the field of cutting machining such as drilling, milling, and turning. Within the fields of drilling and milling, a tool having a rotary character is useful for machining a fixed and movable work-piece.
On the contrary, a machining tool for turning machining is fixed and has the purpose of machining work-piece which is rotating. In general, the machining tool comprises a tool holder and a cutting insert fixed to a mounting surface of the tool holder through a clamping means and contacted with the work-piece.
When a turning machining in which the machining tool is utilized is performed, chips generated on the work-piece by the cutting insert should be separated and removed naturally from the rotating work-piece. If the chips exist between the cutting insert and the work-piece, a surface of the rotating work-piece is influenced by the chips. The above phenomenon is described in more detail as follows.
The effective removal of the generated chips to a large extent depends on the design of cutting insert for controlling effectively the chip. It is preferable that the generated chips are diverted from the cutting area by being deformed, split or broken into relatively short chips with minimal energy consumption and with effective heat dissipation.
To this end, a cutting insert with suitably formed depressions or grooves or a cutting insert with protrusions near the cutting edge which is designed to deform, split or break the chip with minimal energy consumption and with effective heat dissipation is provided.
However, an effective control of chip orientation depends on the positioning of the cutting insert in the tool due to the specific shape of the chip forming groove and a smooth transition between different portions of the chip forming groove.
Thus, the chips formed by the cutting edge will be deflected in the direction toward, rather than away from the work-piece due to the cutting insert positioned in the tool at negative rake angles. Consequently, the work-piece and the tool may be damaged by the chips.
In particular, to machine mild steel generating chips which are difficult to control (that is, not bent easily), the serrated cutting insert is required. In addition, the cutting insert which can remove easily the chips and minimize a cutting load under the machining conditions of a low feed rate and a high depth of cut is required.